# Class A Power Amplifier Online Calculator

This online calculator is for designing Class A power amplifier using BJT(Bipolar Junction Transistor).

## Base Feedback Bias Power Amplifier Calculator

Inputs:

V
V
V
mA

Theoritical Results:
 RB: RC: race: Zinb: Zin: rc: C1: C2: Av:

Equations Used:
$$\newline$$ $$R_{B}=\frac{V_{CC} -V_{BE}}{I_{B}},$$$$\\$$ $$I_{B}=\frac{I_{C}}{\beta},$$$$\newline$$ $$R_{C}=\frac{V_{CC}-V_{C}}{I_{C}}$$ $$\newline$$ $$r_{ace}=\frac{25mV}{I_{E}},$$$$\\$$ $$Z_{inb}=\beta r_{ace},$$$$\\$$ $$Z_{in}=\frac{R_{B}Z_{inb}}{R_{B}+Z_{inb}}(because \hspace{1mm} Z_{in}=R_{B}||Z_{inb}),$$$$\newline$$ $$r_{c}=\frac{R_{C}R_{L}}{R_{C}+R_{L}}(because \hspace{1mm} r_{c}=R_{C}||R_{L}),$$$$\newline$$ $$C_{1}=\frac{1}{2 \pi f 0.1 Z_{in}}(assuming \hspace{1mm} X_{C1} \leq 0.1 Z_{in}),$$$$\\$$ $$C_{2}=\frac{1}{2 \pi f 0.1 r_{c}} (assuming \hspace{1mm} X_{C2} \leq 0.1 r_{c}),$$$$\\$$ $$A_{v}=\frac{r_{c}}{r_{ace}}$$

### Base Biased BJT Amplifier Calculator

The above online calculator for Base Biased BJT Amplifier design helps you to calculate the resistor value for DC bias and the required coupling capacitors and bypass capacitor for AC bias.

## Collector Feedback Bias(Self Bias) Power Amplifier Calculator

Inputs:

V
V
V
mA

Theoritical Results:
 RB: RC: race: Zinb: Zin: rc: C1: C2: Av:

Equations Used:
$$\newline$$ $$R_{B}=\frac{V_{C} -V_{BE}}{I_{C}}$$,$$\newline$$ $$R_{C}=\frac{V_{CC}-V_{C}}{I_{C}}$$,$$\newline$$ $$r_{ace}=\frac{25mV}{I_{E}},$$$$\\$$ $$Z_{inb}=\beta r_{ace},$$$$\\$$ $$Z_{in}=\frac{R_{B}Z_{inb}}{R_{B}+Z_{inb}}(because \hspace{1mm} Z_{in}=R_{B}||Z_{inb}),$$$$\newline$$ $$r_{c}=\frac{R_{C}R_{L}}{R_{C}+R_{L}}(because \hspace{1mm} r_{c}=R_{C}||R_{L}),$$$$\newline$$ $$C_{1}=\frac{1}{2 \pi f 0.1 Z_{in}}(assuming \hspace{1mm} X_{C1} \leq 0.1 Z_{in}),$$$$\\$$ $$C_{2}=\frac{1}{2 \pi f 0.1 r_{c}} (assuming \hspace{1mm} X_{C2} \leq 0.1 r_{c}),$$$$\\$$ $$A_{v}=\frac{r_{c}}{r_{ace}}$$

### About Self Biased BJT Amplifier Design Calculator

The above online self biased BJT amplifier design calculator calculates the resistor values and the coupling capacitor value to bias the BJT transistor and for coupling the ac input source and to the load stage. Self bias method is also called collector feedback method which attempts to stabilize Î² by providing negative feedback of the current back to base. It is more effective biasing method for stabilizing the Q-point than the emitter biasing method

## Emitter Feedback Bias Power Amplifier Calculator

Inputs:

V
V
V
mA
V

Theoritical Results:
 RB: RC: RE: race: Zinb: Zin: rc: C1: C2: C3: Av:

Emitter-Collector Bias Equations:
$$\newline$$ $$r_{ace}=\frac{25mV}{I_{E}},$$$$\\$$ $$Z_{inb}=\beta r_{ace},$$$$\\$$ $$Z_{in}=\frac{R_{B}Z_{inb}}{R_{B}+Z_{inb}}(because \hspace{1mm} Z_{in}=R_{B}||Z_{inb}),$$$$\newline$$ $$r_{c}=\frac{R_{C}R_{L}}{R_{C}+R_{L}}(because \hspace{1mm} r_{c}=R_{C}||R_{L}),$$$$\newline$$ $$C_{1}=\frac{1}{2 \pi f 0.1 Z_{in}}(assuming \hspace{1mm} X_{C1} \leq 0.1 Z_{in}),$$$$\\$$ $$C_{2}=\frac{1}{2 \pi f 0.1 r_{c}} (assuming \hspace{1mm} X_{C2} \leq 0.1 r_{c}),$$$$\\$$ $$A_{v}=\frac{r_{c}}{r_{ace}}$$

### About Emitter Biased BJT Amplifier Design Calculator

The above online emitter biased BJT amplifier design calculator calculates the resistor values, the coupling capacitors values and bypass capacitor values to bias the BJT transistor and for coupling the ac input source and to the load stage.

## Emitter & Collector Feedback Bias Power Amplifier Calculator

Inputs:

V
V
V
mA
V

Theoritical Results:
 RB: RC: RE: race: Zinb: Zin: rc: C1: C2: C3: Av:

Emitter-Collector Bias Equations:
$$R_{E}=\frac{V_{E}}{I_{E}},$$ $$\newline$$ $$R_{B}=\frac{V_{C}-V_{E}-V_{BE}}{I_{B}},$$$$\newline$$ $$R_{C}=\frac{V_{CC}-V_{C}}{I_{C}},$$$$\newline$$ $$r_{ace}=\frac{25mV}{I_{E}},$$$$\newline$$ $$Z_{inb}=\beta r_{ace},$$$$\newline$$ $$Z_{in}=\frac{R_{B}Z_{inb}}{R_{B}+Z_{inb}}(because \hspace{1mm} Z_{in}=R_{B}||Z_{inb}),$$$$\newline$$ $$r_{c}=\frac{R_{C}R_{L}}{R_{C}+R_{L}}(because \hspace{1mm} r_{c}=R_{C}||R_{L}),$$$$\newline$$ $$C_{1}=\frac{1}{2 \pi f 0.1 Z_{in}}(assuming \hspace{1mm} X_{C1} \leq 0.1 Z_{in}),$$$$\\$$ $$C_{2}=\frac{1}{2 \pi f 0.1 r_{c}} (assuming \hspace{1mm} X_{C2} \leq 0.1 r_{c}),$$$$\\$$ $$A_{v}=\frac{r_{c}}{r_{ace}}$$

### About Emitter-Collector Biased BJT Amplifier Design Calculator

The above online Emitter-Collector biased BJT amplifier design calculator calculates the resistor values, the coupling capacitors values and bypass capacitor values to bias the BJT transistor and for coupling the ac input source and to the load stage.

## Voltage Divider Bias Power Amplifier Calculator

Inputs:
V
V

Theoritical Results:

### Equations Used:

AC Power input, $$P_{in} = \frac{v_{in(p-p)}^2}{8 Z_{in(stage)}},$$$$\\$$ AC Power output, $$P_{out} = \frac{v_{out(p-p)}^2}{8 R_L},$$$$\\$$ Power Gain, $$A_p = \frac{P_{out}}{P_{in}},$$$$\\$$ Transistor Power Dissipation, $$P_{DQ} = V_{CEQ}I_{CQ},$$$$\\$$ Power Efficiency, $$\eta = \frac{P_{out}}{P_{DC}},$$$$\\$$ where,$$P_{DC} = I_{DC}V_{CC},$$$$\\$$ $$I_{DC}=I_{bias}+I_{CQ},$$$$\\$$ $$I_{bias}=\frac{V_{CC}}{R_1+R_2},$$$$\\$$ Also used here,
$$I_{E}=\frac{V_{E}}{R_{E}}$$,$$\\$$ and assuming $$I_{CQ} \approx I_{E}$$,$$\\$$ $$r_{ace}=\frac{26mV}{I_{E}},$$$$\\$$ $$Z_{inb}=\beta r_{ace},$$$$\\$$ $$Z_{in}=\frac{R_{1}R_{2}Z_{inb}}{R_{1}R_{2}+R_{1}Z_{inb}+R_{2}Z_{inb}}(because \hspace{1mm} Z_{in}=R_{1}||R_{2}||Z_{inb}),$$$$\newline$$ $$r_{c}=\frac{R_{C}R_{L}}{R_{C}+R_{L}}(because \hspace{1mm} r_{c}=R_{C}||R_{L}),$$$$\newline$$ $$A_{v}=\frac{r_{c}}{r_{ace}}$$

The BJT based class C power amplifier online calculator uses voltage divider biasing method to bias the transistor. This calculator calculates the biasing power gain, efficiency of the class C power amplifier. It also calculates the transistor power dissipation, ac power input and ac power output. The equation used by the calculator is provided above. Voltage divider biasing is best suited for stable operation of the amplifier among the biasing methods. Here the user has to enter the resistors values and the input signal peak to peak voltage and the output signal maximum peak to peak voltage. Also the user is required to enter the base to emitter voltage(Vbe) and the beta of the transistor. One can simplify the design process if the online BJT amplifier calculator is used. Using this calculator the resistors values and the coupling, bypass capacitor values are automatically calculated. The component values obtained there can then be entered into this power amplifier design calculator. For detailed steps and explanations see How to design BJT amplifier with Voltage Divider Biasing